The invention is directed to a heat-fed printing press and to a rotation printing press each respectively having at least one high-performance printing unit that, in particular, is a laser printing unit.
Laser and LED printers are currently distinguished by high-printing performance and printing quality in black-and-white printing. Printing performances of more than 50 pages per minute as well as a printing quality that comes close to that of offset printers are possible. Moreover, the manufacture and the operation of such printers are comparatively cost-beneficial. By contrast thereto, the technical pre-conditions for full-color laser printing are extremely involved and the on-going printing costs are very high.
Ink printers, also called ink jet printers, are often employed in conjunction with personal computers and in plotters since they cost-beneficially enable qualitatively high-grade color prints. The printing speeds obtainable with ink printers, however, are far, far lower then given laser printers so that ink printers have not yet been taken into consideration for the high-performance area.
JP-A-8 221 233 discloses a sheet-fed printing press with a plurality of printers that are respectively arranged at one of a plurality of parallel sheet transport paths. At their input side, these sheet transport paths are connected to a common sheet input path via sheet shunts. At the output side, the sheet transport paths are connected to a common sheet output path via sheet intermediate stores. The parallel arrangement of printing units serves the purpose of nonetheless being able to continue the printing process with the further available printing units given outage of one of the printing units. The printing of a sheet by at least two printing units is not addressed in this document. A bypassing of one of the printing units arranged parallel and a delivery of the sheets directly to the sheet output paths is also not disclosed in this document.
U.S. Pat. No. 5,140,674 discloses a serial arrangement of a color printer and a following monochromatic printer. Both printers print the same sheet, two-color printing being possible as a result thereof. The serial arrangement of the two printers leads thereto that the printing unit with the lowest printing speed defines the speed of the printing process and, thus, the throughput of sheets.
EP-A-0 737 570 discloses a printing press with a plurality of printing units. These printing units are arranged serially following one another, i.e. the overall printing speed and the throughput of sheets is defined by the printing unit with the lowest printing speed. The printing units can also work according to different printing processes.